A098870 Sum of the cubes of the digits of the previous term, starting with 2.

2, 8, 512, 134, 92, 737, 713, 371, 371, 371, 371, 371, 371, 371, 371, 371, 371, 371, 371, 371, 371, 371, 371, 371, 371, 371, 371, 371, 371, 371, 371, 371, 371, 371, 371, 371, 371, 371, 371, 371, 371, 371, 371, 371, 371, 371, 371, 371, 371, 371, 371, 371, 371

Offset: 1

Author

Gary Nagel (gary.nagel(AT)sendit.nodak.edu), Oct 12 2004

Keywords

• nonn
• base

Comments

A student of mine (Dennis Vadner) noted this sequence when working with the sequence formed by summing the squares of the digits of the previous term for a class assignment. Upon investigating various initial terms, it was noted that there appeared to be a limited number of end behaviors.

Examples

			Since a(5) = 92, a(6) is therefore 9^3 + 2^3 = 729 + 8 = 737.
		

Links

• Erich Friedman, What's Special About This Number?, 371.
• Index entries for linear recurrences with constant coefficients, signature (1).

Crossrefs

Cf. A000216.

Programs

Mathematica

FixedPointList[Plus@@(IntegerDigits[#]^3) &, 2] (* Alonso del Arte, Mar 18 2020 *)
PadRight[{2,8,512,134,92,737,713},100,{371}] (* Harvey P. Dale, Oct 20 2024 *)

Formula

G.f.: x*(342*x^7 + 24*x^6 - 645*x^5 + 42*x^4 + 378*x^3 - 504*x^2 - 6*x - 2) / (x - 1). - Jinyuan Wang, Mar 18 2020

Extensions

Offset changed to 1 by and more terms from Jinyuan Wang, Mar 18 2020